Wooden bicycle build

[BartRidesEternal]

Hi guys,

This is a tryout for me.
I watched a awesome movie the other day called "Porco Rosso" and got into a great conversation with a friend and fellow nerd about World War One planes.
Wood, steel, oil, craftmanship, danger and freedom. I think that makes for a great concept.

I instantly got ideas for a wooden bicycle and wood/steel joinery. I searched for inspiration on pinterest and here I am writing a thread with plans to build a wooden bicycle.

So what are my intentions? Geometry? Style? Practicality? Use?

I'll let it evolve while planning and building, but my first ideas and thoughts are as follows:

-Antique style in looks and build. You have these beautiful modern laminated bicycles, but I am not going for that. I am aiming for antique, rough, oily, greasy used looks. Antique screws/bolts and nuts. Steel joinery by brazing or rivets if the budget allows it.
I would love the "Elgin Twin" in wood aswell.

-Geometry. Not fully decided on that too. I absolutely enjoy my Porucho build and my self built "Pope Roger" bike. So I measured both, pictures below.

-Use/Practicality: Able to ride hundreds of kilometres on a day with it. Just for fun sunny-day tours. Not necessarily a rack for luggage.
Haven't decided on fenders, although I love the looks of my mahogany wooden fenders.

Inspiration pictures (not mine) and then my notes and parts pile:

Found this picture on Ratrodbikes. I just really enjoy that rough look and shape. Thanks!

Industrial looks, awesome!

Not antique, more vintage, but potential!

Very similar and simple build found on instructables.

Not rough, but gorgeous nonetheless!

Checkout that left cruiser.

This looks antique, oily. 1898 I believe. This picture alone makes me drool.


My own notes and ideas so far:

Geometry comparison between my bicycles.

My parts pile:

1940 Wooden wheelset with Torpedo coasterbrake hub.

Choice between candle lamps.

Stem, very old and nice!

Stamp brake!

So lots of thoughts and ideas.
I enjoy restoring a bike, but then a crucial piece of creativity is missing for my experience. I enjoy design freedom.
It will certainly be a large bicycle.

First I will make more concepts and notes. And plan for materials, wood type and joinery.
Then I will think of a assembly JIG. The most crucial parts need alignment: Bottom bracket shaft.
The wheel axles and their frame dropouts.
Seat tube (if there is a seat tube). Seat log?

Thanks for reading!

 

[rickpaulos]

The very first bicycle was made of wood and there have been countess wood bikes since. You can do what every you want.
Lots of variations on natural material have been used. Bamboo bikes, fibre mixed with epoxies (Schwinn even sold one). There are the engineering student contests where the entire bike must be made from a single sheet of plywood with no other hardware and be rideable. Most wood bikes I've seen are a mix of wood with regular bicycle parts integrated into the design.

 

[Kevin B]

I've looked at this on Amazon a few times. Bamboo Bicycle Kit

I have seen books about wood bicycles on Amazon too. This is a very interesting topic.

 

[BartRidesEternal]

The very first bicycle was made of wood and there have been countess wood bikes since. You can do what every you want.
Lots of variations on natural material have been used. Bamboo bikes, fibre mixed with epoxies (Schwinn even sold one). There are the engineering student contests where the entire bike must be made from a single sheet of plywood with no other hardware and be rideable. Most wood bikes I've seen are a mix of wood with regular bicycle parts integrated into the design.

Yeah I have seen these contests, very creative!

I've looked at this on Amazon a few times. Bamboo Bicycle Kit

I have seen books about wood bicycles on Amazon too. This is a very interesting topic.

Pretty neat! And thank you.

More inspiration from myself:

I am drawing while listening to some music (I am not that good):

Pathracer with a curved second top tube, wing nuts and a carbide lamp. Guy with a pipe (smokestack!) and 'peaky blinders' cap as a rider. Love it!

And the following picture is our kitchen. 8 years ago we were looking for a new kitchen. Since prices at kitchen shops were ridiculous we bought an antique workbench to convert into a kitchen. Its an eyecatcher! And you can understand what kind of wood I love to look at:

 

[BartRidesEternal]

So I studied that old picture that I found on Ratrodbikes and started on some notes and ideas regarding that interesting frame.
Some things I noticed:
-Elevated chainstay.
-No seat tube, but two riggers and the front sprocket seems to be on the inside.

Here's the picture again:

The text on this newspaper article said its made of Ash.

Here are some notes and ideas regarding that bottom bracket:

Idea to adapt an JIS square taper crankarm.
I can machine a shaft myself if needed.

More notes and stress calculations needed if I want to go this way.

Next: Geometry. I measured two bicycles and decided to go halfway, since this time I do not want a too 'high and upright' bicycle like Pope Roger and not as low as my Porucho 'antique motorcycle style' build. The biggest downside of the Porucho frame in my opinion is the low and upfront bottom bracket.

Measurements are slapped on there for note purposes, not very tidy. Have a reputation to uphold!
With these measurements I'll know what JIG size I need and possible frame wood sizing.

Without measurements, so I can print this and sketch frame shape ideas.

Pictures above: the bikes I took measurements from.

Thanks for your interest!

I will keep you in the loop of my "rollercoaster" thought process.

 

[axeman88]

The challenge with designing structures from wood is that they do very well handling stress along the grain, and very VERY poorly across the grain. Boat builders back in the day would spend considerable time searching for naturally occurring crooks and bends that they could use for those elements of the frame that required a complex shape.

Sawing a curve from a piece of wood that has grain will generally result in some portion of the element being cross grain, and that's where it will break.

Plywood is one way around this, steam bending is another, using wood as a cosmetic cladding over metal is a third.

Designing stressed elements as straight sections of select wood is how the problem is usually solved.
Like how one would build their chukudu:

Even here, time spent going through a big pile of lumber at the lumber yard, to find a few sticks for a project is part of the process. Most of the stuff that they want good money for at your local home center, would have been cut up and tossed in the woodstove by our grandfathers.

I think all of Miyazaki's work is inspiring for those who are mechanically inclined. You may also enjoy "Howl's Moving Castle", "Ponyo", and "The Wind Rises"

 

[rickpaulos]

I spotted these on Ragbrai 2021. Actually being ridden! Okay, ridden in an overnight town, not necessarily from town to town. 75 miles on a wood seat? Pass.

 

[rickpaulos]

Another Ragbrai. Like the font that matches Trek's for some years. Some wood bikes are works of art. Some are like this:

 

[Ulu]

I think we invented welding so we wouldn’t have to do this. But as a curio it has unlimited potential.

 

[BartRidesEternal]

The challenge with designing structures from wood is that they do very well handling stress along the grain, and very VERY poorly across the grain. Boat builders back in the day would spend considerable time searching for naturally occurring crooks and bends that they could use for those elements of the frame that required a complex shape.

Sawing a curve from a piece of wood that has grain will generally result in some portion of the element being cross grain, and that's where it will break.

Plywood is one way around this, steam bending is another, using wood as a cosmetic cladding over metal is a third.

Designing stressed elements as straight sections of select wood is how the problem is usually solved.
Like how one would build their chukudu:

Even here, time spent going through a big pile of lumber at the lumber yard, to find a few sticks for a project is part of the process. Most of the stuff that they want good money for at your local home center, would have been cut up and tossed in the woodstove by our grandfathers.

I think all of Miyazaki's work is inspiring for those who are mechanically inclined. You may also enjoy "Howl's Moving Castle", "Ponyo", and "The Wind Rises"

Thank you Axeman, I am aware regarding the grain direction, but I appreciate your heads-up!
In my previous post I showed a two pronged fork shape which would definitely have issues with strength if one were to use a plank.

The Chukudu is awesome! Great practical tool. I wonder what they use for the wheels. Bearings or wood with lots of grease.

The Wind Rises is one of my favorite movies of all time A masterpiece in my opinion.

I spotted these on Ragbrai 2021. Actually being ridden! Okay, ridden in an overnight town, not necessarily from town to town. 75 miles on a wood seat? Pass.

View attachment 221744View attachment 221745View attachment 221746

Beautiful! Those bikes look the part!

Another Ragbrai. Like the font that matches Trek's for some years. Some wood bikes are works of art. Some are like this:

View attachment 221759View attachment 221760

Wow thats sick! Not really my taste but I'm impressed.

I think we invented welding so we wouldn’t have to do this. But as a curio it has unlimited potential.

Woodworking grew on me the past years. I still like steel and welds though

 

[BartRidesEternal]

Some more concept updates.
Decided to draw some and work one out in 3D.
Since my first thoughts were to use old scrap wood, I chose to work one out that doesnt require wood bending, which would take a bending jig, lamination and/or steam bending. For this moment that is too much work. Maybe there is more time (and space in the shed) next year.

Plus: the black/white picture earlier is hard to build with the double "seat tube" parts. I have a tendency to go easy, cheap, antique and nasty for this first learning experience.

Enjoy the concepts, let me know which one you liked most!

Above: decided to work this one out first.

Now I should know the length and thickness of scrap wood to look for.
I will be selective regarding the thickness and density of the wood and its location on the frame.

And workout the details.

Thanks guys!

 

[rickpaulos]

Before picking up any ole scrap wood, check the charts for strengths of each type of wood. Oak, Ash, Mahogany, Pine, etc. I used a bit of Scotch Pine for my first bike related build and it lasted about 10 minutes. I rebuilt using Orange Osage (grows Hedge Apples) & Douglas Fir and that is still holding up after a 1000 miles of abuse by many riders.

Many wood workers go for artistic beauty and mix dark & light. Cherry & White Oak for example.

 

[axeman88]

Some more concept updates.
Decided to draw some and work one out in 3D.

Enjoy the concepts, let me know which one you liked most!

View attachment 221786
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Above: decided to work this one out first.
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Now I should know the length and thickness of scrap wood to look for.
I will be selective regarding the thickness and density of the wood and its location on the frame.

And workout the details.

Thanks guys!

Your 2nd concept looks the best to me, in terms of strength and efficient use of material. It's similar to a couple designs that you posted for inspiration, and not dis-similar to the 4th concept image you posted. I think that the reverse bow shapes, without the "S bend" of concept 4 would provide the stiffest structure. You might even want to pre-stress the bows either away from, or towards each other. Pre-stressing is often engineered into structures to prevent reversing tensile stresses that lead to fatigue failure. When this method is followed, as a structure is loaded and unloaded, tensile stresses go from moderate to high but never reverse, due to the preload.

You'll want to gusset the joints at the head and the rear axle. Notice how the builder of the bike in pic #3 of your opening post used metal to reinforce the axle joint, and also the stacked laminations at the head. The curve cut into the head structure isn't just decorative, it helps distribute the stress into the frame elements. Also notice how this builder has stacked the laminations of light and dark lumber, which I suspect was steam bent to the desired shape. Laminating, means that flaws and grain structures in individual layers will have less influence on the overall strength of the structure, the flaws are "averaged out". In plywood, grain directions on alternate layers are at right angles. I doubt cross grained layers would be valuable for these designs, but it will depend on the particulars of the structures.

I am seeing structural issues with your CAD developed "stick design". The joints don't look strong enough nor resistant to relative rotation of one element with another. Gussets will probably be needed. They can be thin material if arranged with their widest dimensions arranged in opposition to the loads. Going back to Porco Rosso, those early airplanes appeared to be stick structures, but they weren't only the sticks. The wires were essential tension elements, and the fabric covering stabilized the entire structure. Keep this in mind if you use stick structures.

Since you are using CAD, perhaps you have access to stress analysis tools? Solidworks has a simple FEA package built in that would allow you to visualize the stresses from basic static loading to guide and refine your design before you've committed valuable materials and labor. FEA analysis of 3D models results in images like this, where the colors are referenced to different levels of stress:

One analyzes their model, makes changes, and re-analyzes until the design seems viable.

There's other methods, ...
As a young engineer, I would sketch individual sections of complex structures and use simple mathematical stress analysis to get in the ballpark, but there is considerable math involved.

There is another method that goes back to the 1930s, that might be valuable. It's primarily for 2D stress analysis, but it seems to me, a bicycle frame is largely a 2D structure. The method uses the principle of Photoelasticity. Simple models are cut from clear material which deforms (strain) in response to imposed stresses from loads. The strain creates visual color fringes which correspond to levels of stress. By first bending some simple structures with easily analyzed mathematical models, one would even have some idea of what level of stress the different colors corresponded to.

In this image a protractor is being squeezed. The local strain, which can be seen via the colored fringing, is proportional to the local stress, which can't be seen, at least while the material is within its elastic range:

https://en.wikipedia.org/wiki/Photoelasticity
Even if your models aren't cut from cast acrylic, I think you'd be wise to build some simple models, of some cheap fairly homogeneous material, and load them to see where they break, and under what load. When a structure doesn't break consistently in the same spot, it's at least somewhat optimized. I'd guess that your final version would be at least 4 times stronger than your first attempt.

 

[CDubya]

This is fascinating, and some of you guys have amazing skills/knowledge. Thanks for the many pics, drawings, tips, etc. and for those yet to come!

 

[Ulu]

50 years ago, we did something called brittle lacquer analysis. I did some carabiners for mountain climbing.

You basically paint your model or your prototype in a very brittle paint.

Then you can do various things to it, like get it very cold and see where it cracks from material shrinkage, or twist it, bend it, & stretch it in different directions to see where the paint would crack: because that’s where your stress concentrations were.

Where you had heavy stress concentration, there would be lots of cracks very close together, and the flow lines of those cracks would show you the pattern of stress distribution throughout the surface of the structure.

Wherever the metal strained, that is where it stretched, the paint cracked. The theory is that where you got all the close cracks in the paint is where the metal was going to crack first.

 

[SwissGuy]

Another Ragbrai. Like the font that matches Trek's for some years. Some wood bikes are works of art. Some are like this:

View attachment 221759View attachment 221760

I must say, I like the axe carrier concept!

 

[BartRidesEternal]

Before picking up any ole scrap wood, check the charts for strengths of each type of wood. Oak, Ash, Mahogany, Pine, etc. I used a bit of Scotch Pine for my first bike related build and it lasted about 10 minutes. I rebuilt using Orange Osage (grows Hedge Apples) & Douglas Fir and that is still holding up after a 1000 miles of abuse by many riders.

Many wood workers go for artistic beauty and mix dark & light. Cherry & White Oak for example.

Awesome, thanks!
Do you have a picture of your bicycle? Getting curious here

Your 2nd concept looks the best to me, in terms of strength and efficient use of material. It's similar to a couple designs that you posted for inspiration, and not dis-similar to the 4th concept image you posted. I think that the reverse bow shapes, without the "S bend" of concept 4 would provide the stiffest structure. You might even want to pre-stress the bows either away from, or towards each other. Pre-stressing is often engineered into structures to prevent reversing tensile stresses that lead to fatigue failure. When this method is followed, as a structure is loaded and unloaded, tensile stresses go from moderate to high but never reverse, due to the preload.

You'll want to gusset the joints at the head and the rear axle. Notice how the builder of the bike in pic #3 of your opening post used metal to reinforce the axle joint, and also the stacked laminations at the head. The curve cut into the head structure isn't just decorative, it helps distribute the stress into the frame elements. Also notice how this builder has stacked the laminations of light and dark lumber, which I suspect was steam bent to the desired shape. Laminating, means that flaws and grain structures in individual layers will have less influence on the overall strength of the structure, the flaws are "averaged out". In plywood, grain directions on alternate layers are at right angles. I doubt cross grained layers would be valuable for these designs, but it will depend on the particulars of the structures.

I am seeing structural issues with your CAD developed "stick design". The joints don't look strong enough nor resistant to relative rotation of one element with another. Gussets will probably be needed. They can be thin material if arranged with their widest dimensions arranged in opposition to the loads. Going back to Porco Rosso, those early airplanes appeared to be stick structures, but they weren't only the sticks. The wires were essential tension elements, and the fabric covering stabilized the entire structure. Keep this in mind if you use stick structures.

Since you are using CAD, perhaps you have access to stress analysis tools? Solidworks has a simple FEA package built in that would allow you to visualize the stresses from basic static loading to guide and refine your design before you've committed valuable materials and labor. FEA analysis of 3D models results in images like this, where the colors are referenced to different levels of stress:
View attachment 221848

One analyzes their model, makes changes, and re-analyzes until the design seems viable.

There's other methods, ...
As a young engineer, I would sketch individual sections of complex structures and use simple mathematical stress analysis to get in the ballpark, but there is considerable math involved.

There is another method that goes back to the 1930s, that might be valuable. It's primarily for 2D stress analysis, but it seems to me, a bicycle frame is largely a 2D structure. The method uses the principle of Photoelasticity. Simple models are cut from clear material which deforms (strain) in response to imposed stresses from loads. The strain creates visual color fringes which correspond to levels of stress. By first bending some simple structures with easily analyzed mathematical models, one would even have some idea of what level of stress the different colors corresponded to.

In this image a protractor is being squeezed. The local strain, which can be seen via the colored fringing, is proportional to the local stress, which can't be seen, at least while the material is within its elastic range:
View attachment 221849
https://en.wikipedia.org/wiki/Photoelasticity
Even if your models aren't cut from cast acrylic, I think you'd be wise to build some simple models, of some cheap fairly homogeneous material, and load them to see where they break, and under what load. When a structure doesn't break consistently in the same spot, it's at least somewhat optimized. I'd guess that your final version would be at least 4 times stronger than your first attempt.

I am learning a lot here, I never knew about photoelasticity, very cool!

I agree with you on which concepts are the best strength wise. My 'modeled' concept isnt the best now that I start looking at the joints. I did like that offset seatpost, just like the 'Electra Ratrod' bicycle.

I am performing analysis, but just some quick maths and tension checks too see if the design and joints are viable.
The weakest thing in the joints is mostly the splitting of the wood near screws of rivets. Thats why a joint needs a lug of a steel part that holds it, if you know what I mean.

A bit like this:

Maybe I'll do some 3D analysis when I have modeled something near the end result. Really interested if these are near my own calculations.
I have lots of data of a Dutch website regarding wood. Laminated and solid, depending on how its is cut.

Thanks, I appreciate your share of information! As a mechanical engineer I can learn from other engineers, but from everyone for that matter.

50 years ago, we did something called brittle lacquer analysis. I did some carabiners for mountain climbing.

You basically paint your model or your prototype in a very brittle paint.

Then you can do various things to it, like get it very cold and see where it cracks from material shrinkage, or twist it, bend it, & stretch it in different directions to see where the paint would crack: because that’s where your stress concentrations were.

Where you had heavy stress concentration, there would be lots of cracks very close together, and the flow lines of those cracks would show you the pattern of stress distribution throughout the surface of the structure.

Wherever the metal strained, that is where it stretched, the paint cracked. The theory is that where you got all the close cracks in the paint is where the metal was going to crack first.

Thats sound pretty interesting too. Very practical method of analysis. Thanks for that lesson Ulu!

I must say, I like the axe carrier concept!

Decapitation or log splitting after a wheelie

 

[BartRidesEternal]

So thanks to your advice, me drawing some wood/steel joinery and doing a quick analysis made me throw that 3D modeled concept in the digital trash.
no offence!

I was thinking of a steel bottom bracket like this:

This one has bamboo though.

But then I found my 1930's scrap frame that I found a long time ago.
I also made a topic in 2021 here on RRB to restore this frame with wood (sorry moderators ) and instantly started measuring and writing down new ideas.
Also did a few chainstay strength calculations with maple wood and oak. (Cut the chainstay and fabricate a wood one).

So almost built from scratch then.

Enjoy the pictures! My frame first, then concept sketches and measurements and then some inspiration pictures (again).

Some inspiration:

Last picture: I like that 'hanging' disc brake caliper mount. Maybe I can do that with the coasterbrake mount. I know its not the best option in terms of strength, but I care for looks aswell

 

[Ulu]

You always want lots of edge distance on fasteners in wood. 7 to 8 bolt diameters for tension joints in most woods. 5 to 6 in the very hardest.

So normally a 5mm screw would want to be 25 to 40 mm in plus half the screw dia. to the center. Best to use other methods of anchorage against tension.

In structural work, connections with steel teeth keep things stable.

 

[rickpaulos]

This a favorite wood & copper (plated) bike.